This invention relates to a modular printhead. More particularly, the invention relates to the assembly of such a modular printhead. Specifically, this invention relates to a method of assembling a printhead.
The applicant has previously proposed the use of a pagewidth printhead to provide photographic quality printing. However, manufacturing such a pagewidth printhead having the required dimensions is problematic in the sense that, if any nozzle of the printhead is defective, the entire printhead needs to be scrapped and replaced.
Accordingly, the applicant has proposed the use of a pagewidth printhead made up of a plurality of small, replaceable printhead modules which are arranged in end-to-end relationship. The advantage of this arrangement is the ability to remove and replace any defective module in a pagewidth printhead without having to scrap the entire printhead.
It is also necessary to accommodate thermal expansion of the individual modules in the assembly constituting the pagewidth printhead to ensure that adjacent modules maintain their required alignment with each other.
According to the invention there is provided a method of assembling a printhead, the printhead having a receiving means and a plurality of printhead modules arranged end-to-end in the receiving means, the method comprising the steps of
upon completion of manufacturing of the receiving means, testing each bay of the receiving means in which a module will be received to determine a manufacturing offset from specification for that bay;
selecting a printhead module having a manufacturing offset from specification which accommodates the offset of the bay of the receiving means for which it has been selected; and
inserting the selected printhead into its associated bay of the receiving means.
The method may include, after manufacturing each printhead module, testing the printhead module to determine its manufacturing offset. Further, the method may include marking each tested printhead with its manufacturing offset.
The method may include storing all tested printhead modules having the same manufacturing offset together in a storage zone. Then, the step of selecting the printhead module may include removing the selected printhead module from its designated position in the storage zone.
The method may include using a statistical analysis process to ensure use of a very large majority of the modules. The applicant believes that, in fact, by use of the statistical analysis process, almost all the modules, if not all, will be used. The statistical analysis tool used may be a central limit theorem.